CRUSTACEA OF NEW ZEALAND. 245 



pleopoda are specially modilicd, the penial filament being formed from a portion of the 

 endopodite, a lact that will perhaps be useful to throw light on the more modified 

 second pleopoda in the males of various Asellidse, &c. 



(3) A consideration of the coxse of Phreatoicus leads to a short discussion in support 

 of Spence Bate's contention that the "epimera " or " side-plates " are in reality the coxae 

 of the appendages of the perajon. 



(4) In discussing the systematic jjosition of Phreatoicus reference is made to the 

 external characters by which the Amphipoda are separated from the Isopoda, and an 

 additional difference is shown to exist in the ischia of the appendages of the peraeon, as 

 these ai;e of moderate length in all Isopoda except the Apseudidaj and Tanaidse, while 

 they are almost always very short in the Amphipoda. 



(5) The genus Cruregens, belonging to the Anthuridae, is described and compared 

 with some allied genera. It has only six pairs of legs, and thus appears to perma- 

 nently retain this laiTal character of the Isopoda, owing probably to an arrest of 

 development. 



(6) The mouth-parts of Cruregens, which are very difficult to determine, are fuUv 

 described, and it is shown that the mandibles are small and without any trace of a 

 palp — a character very exceptional in the Anthuridae. 



(7) The terminal uropoda of Cruregens are shown to consist of an oblong peduncle, 

 a long narrow exopodite arising from near the anterior end of the peduncle, and a 

 one-jointed endopodite arising from its posterior end. Other authors, with the exception 

 of Dohrn, have apparently wrongly described the uropoda of the Anthuridae as having 

 a two-jointed endopodite, the distal portion of the peduncle having been mistaken for a 

 part of the endopodite. 



(8) The telsou of Cruregens and of some other Anthurids is distinctly separated from 

 the last segment of the pleon, though this is exceptional among the Isopoda. 



(9) The genus Crangonyx is discussed at some length, and the mouth-parts of 

 Crangonyx com])actus arc described. The mouth-parts of Crangonyx do not appear to 

 have been previously described. 



(10) The pleopoda of Crangonyx compactus have each only one ramus instead of iwo, 

 as is almost universally tlie case in other Amphipoda. It appears to be the inner brancli 

 that is wanting. Nothing appears to be known of the pleopoda of most of the other 

 si)ecies of Crangonyx. 



(11) The species Gammarus fragilis appears to correspond well with the characters 

 usually assigned to the genus, but it is interesting to note tliat the jjrcsent species has 

 very long antennae, peraeopoda, and terminal uropoda, thus showing some approach to 

 the characters of Niphargvs. 



32* 



